Fig. 2.

A, Light/dark stress-induced plasma corticosterone values (micrograms per deciliter) for LR and HR rats at various times (15, 30, 60, and 90 min) after the termination of 5 min light/dark stress and in control rats that were not exposed to the light/dark anxiety test (i.e., t = 0). Basal plasma corticosterone concentrations did not differ between the HR and LR rats. However, the HR rats exhibited greater stress-induced secretion of corticosterone measured 15 and 30 min after termination of the anxiety test. B, Restraint stress-induced plasma corticosterone values (micrograms per deciliter) for LR and HR rats at various times (30, 90, and 120 min) after the termination of 30 min restraint stress and in control rats that were not exposed to the restraint stress (i.e., t = 0). Neither the basal (t = 0) nor the stress (t = 30, 90, and 120 min) level of corticosterone was different between HR and LR rats. Data are expressed as mean ± SEM. *p< 0.05.